Substantial efforts have been made in the art to produce egg replacer compositions which provide nutritional values similar to natural eggs, but which do not include certain undesired properties of natural eggs. For example, the American Heart Association recommends that the percentage of calories from saturated fat in the daily diet be from about 4 to 5%, while the percentage of calories from polyunsaturated fat be from about 10 to 11%. Additionally, it is recommended that the amount of cholesterol in the daily diet be substantially restricted. However, the yolk of natural eggs is relatively high in both saturated fats and cholesterol. Thus, while eggs are relatively low in calories and have high nutritional value, eggs are often restricted in the diet for reasons of the relatively high amount of saturated fats and cholesterol in the egg yolk. Such restrictions on the intake of eggs not only eliminates a nutritional food from the diet, but additionally often disrupts eating patterns of long standing, i.e. the intake of eggs particularly for breakfast. Such disruption of long standing eating patterns has an adverse phychological effect upon the dieter.
For the foregoing reasons, there has been a substantial effort in the art to provide egg replacers which are sufficiently palatable as to be accepted by the dieter but which is yet low in saturated fats and cholesterol. The approaches in the art, generally, have been to duplicate the natural egg wherever possible and to deviate from the natural constituents of eggs only where necessary, e.g. in the use of unsaturated fats and the elimination of cholesterol. Thus, the general approach in the art is that of using natural egg whites in egg substitute materials, since the white per se does not substantially contribute to the above discussed difficulties with natural egg. The "yolk" of the egg replacer is then compounded from combinations of unsaturated oils, minerals and vitamins so as to as closely as practical approximate the nutritional characteristics of the yolk, absent of the saturated fats and cholesterol.
These efforts in the art have met with substantial success, but on the other hand these efforts have resulted in compositions which present other problems to the consumer. These problems have so complicated the use of presently available egg substitute compositions that consumer acceptance has been substantially less than that anticipated by the art.
For example, natural egg whites used in conventional egg substitute compositions, are subject to relatively rapid bacterial action and degradation once the white is removed from the egg shell. Thus, provisions must be made in the conventional compositions to retard this bacterial action. Also, as is known in the art, the drying of egg whites, e.g. spray drying, introduces substantial unwanted off-flavors in the egg whites and, therefore, the dried form of conventional egg replacer compositions have never been accepted by the consuming public. This requires that the conventional compositions be transported and stored in a frozen form or under refrigeration, and even then the shelf life is relatively short.
Natural egg whites also contain about 0.05% of avidin, a glycoprotein that combines with biotin making the biotin biologically unavailable. A 50 gram egg contains approximately 1.76 mg. of avidin and 11.2 mcg. of biotin. Avidin, which has a molecular weight of about 64,800, contains four subunits each of which combines with one molecule of biotin (molecular weight about 244.3). Thus, each milligram of avidin will combine with about 15.1 mcg of biotin, and the approximately 1.76 mg of avidin in a 50 gm egg has, therefore, the potential for combining with about 26.6 mcgs of biotin. Since a 50 gm egg contains only about 11.2 mcg of biotin, sufficient avidin remains to combine with 15.4 mcgs of biotin from other sources. Avidin is extremely resistant to proteolytic digestion and the association of biotin with avidin makes the biotin unavailable for nutritional use. The resulting avidin/biotin complex possesses a high association constant and is very resistant to heat.
Accordingly, it will be appreciated that when a natural egg is thoroughly mixed, essentially all the biotin is made nutritionally unavailable by combining with avidin and that complexed biotin is still unavailable after cooking. Fortunately, some uses of whole eggs do not result in such total mixing of the yolk and white and formation of the avidin/biotin complex is substantially reduced. On the other hand, many conventional egg substitutes use egg white as the functional ingredient and this ingredient is intimately mixed with the substitute "yolk" which will contain biotin if an effort has been made to duplicate the materials and vitamins in natural egg. Thus, in special hospital or emergency feeding where there is limited food intake and thus limited biotin intake, biotin deficiencies may occur when conventional egg substitute materials, based on natural egg whites as protein sources, form a significant portion of the diet.
Additionally, conventionally available compositions, based on egg white as the protein source, have experienced difficulty in being adequately formulated for reproducing the physical property necessary for simulating a scrambled egg and at the same time simulating the physical properties imparted by eggs in conventional recipes, e.g. custards, puddings and the like. Thus, generally speaking, the egg replacer compositions have been essentially formulated to simulate scrambled eggs in the cooked form and the properties of these compositions have not allowed widespread use in recipes and in a manner which will essentially duplicate natural egg. On the other hand, if formulations are prepared for duplicating the physical properties of egg in a recipe, the scrambled egg form is often unacceptable to many of the consuming public.
It would, of course, be of considerable value in the art to provide egg replacer compositions which retain the advantages of the conventionally available compositions, but while on the other hand avoid the difficulties associated therewith.